Stabilizing rice bran and rice bran products

ABSTRACT

A process for stabilizing rice bran containing protein and a naturally occurring lipase enzyme that causes rancidity. The rice bran is treated with an antilipase enzyme, preferably a nonspecific protease of plant or fungal origin. Treatment with the antilipase enzyme stabilizes the rice bran against rancidity without denaturing the protein. Stabilized rice bran has food and industrial utility and can be processed by a sequence of steps including wet milling and microfiltration into a variety of other products also having food and industrial utility. In some instances depending on the product, it is not necessary stabilize the rice bran before wet milling and microfiltration.

This is a division, of application Ser. No. 07/975,527, Nov. 12, 1992,now U.S. Pat. No. 5,292,537.

The present invention relates to a method for enzymatically stabilizingrice bran and to products produced from stabilized and unstabilized ricebran, included among which is a rice bran milk-replacer.

BACKGROUND OF THE INVENTION

When harvested from the field, rice is in the form of paddy or roughrice, where the kernel is enveloped by a rice hull. After being dried,rice for human consumption is first milled to remove the hull, yieldingbrown rice. In a second stage of milling, the outer brown layer isremoved from the rice kernel to yield polished or white rice. Dependingon the milling techniques, rice bran may include part of the germ and itmay also be mixed with part of the hull.

The composition of rice bran (in percent by weight) is generally 11-13%of water, 18-21% of crude fat and oil, 14-16% crude protein, 8-10% ofcrude fiber, 9-12% of ash and 33-36% of carbohydrate. Rice bran hasnaturally occurring lipases that hydrolyze the oil into glycerol andfree fatty acids which give the product a rancid smell and taste. Undernormal milling conditions (ambient temperatures above freezing), ricebran will degrade in approximately six hours into an unpalatablematerial which is not suitable as a human food. Because of the problemwith rancidity, most rice bran is used as feed for animals or asfertilizer or fuel.

The oil from rice bran is sometimes extracted for use as human food.Because of the lipases, most extractions are carried out close to thegrowing areas in small capacity rice mills. To obviate this problem,others have found that naturally occurring lipases can be deactivated byheating the rice bran for a snort period of time, as for example bypassing it through a high temperature high pressure extruder. The heatstabilizes the rice bran such that it can be transported to a centraloperation for extraction of the oil but the protein is denatured by theheat such that the rice bran is unfit for use in the manner of thepresent invention.

SUMMARY OF THE INVENTION

An important object of the present invention is to provide a process forstabilizing rice bran by deactivating naturally occurring lipaseswithout denaturing the rice bran's protein or otherwise altering itsphysical or chemical properties. The process may be advantageouslyapplied to the rice bran in conjunction with milling on a local basisclose to the rice growing fields with the stabilized rice bran beingtransported to a centralized facility for further processing. Anotherobject is to provide a process which realizes the full nutritionalpotential of rice bran in a number of useful products including a ricebran milk-replacer. Other objects and features of the invention will bein part apparent and in part pointed out hereinafter.

In accordance with the invention, rice bran containing protein andhaving a naturally occurring lipase enzyme that causes rancidity isstabilized without denaturing the protein. An antilipase enzyme isselected which inactivates the naturally occurring lipase enzyme in therice bran. The rice bran is mixed with water and with the antilipaseenzyme. The antilipase enzyme is provided in an amount effective tosubstantially inactivate the lipase enzyme in a period of time that is afunction of the amount of water present in the mix. At the end of theinactivation period, the rice bran is stabilized against ranciditywithout denaturing the protein. The wet stabilized rice bran can bedried or processed into other products for use in food or industry.

The wet stabilized rice bran can be wet milled (sometimes with pHadjustment) and the soluble dietary fiber separated as a liquid phasefrom the insoluble dietary fiber. The protein and other nutritionalcomponents of the rice bran such as starch, minerals, vitamins and soforth pass mainly in the liquid phase. Optionally the starch in theliquid phase can be converted into dextrins and dextroses by applicationof acid, heat and/or amylases. The liquid phase is microfiltered (with amolecular weight cut-off of 100,000 or greater) and then ultrafiltered(with a molecular weight cut-off of 10,000 or greater) to producevarious products having food or industrial utility. Depending on theproduct to be produced from rice bran, in some instances, it is notnecessary to stabilize the rice bran before it is wet milled andprocessed as described above.

The invention summarized above comprises the methods and productshereinafter described, the scope of the invention being indicated by thesubjoined claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, in which several of various possibleembodiments of the invention are illustrated,

FIG. 1 is a schematic flow sheet of a method for stabilizing rice branin accordance with the present invention;

FIG. 2 is a schematic flow sheet showing further processing of astabilized full-fat or partially defatted rice bran in accordance withthe present invention to produce, inter alia, a milk-replacer; and,

FIG. 3 is a schematic flow sheet showing further processing of astabilized rice bran in accordance with the present invention to producevarious products other than a milk-replacer.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is concerned with a series of processing steps bywhich a number of novel products are obtained from rice bran. It startswith freshly milled rice bran which is provided as a flour preferablyground to the point that all of the material will pass through a 40 meshscreen. The rice bran has a naturally occurring lipase which tends tohydrolyze the oil in the rice bran into glycerol and fatty acids.Suitable starting materials include recently milled (unhydrolyzed)full-fat rice bran, low-fat rice bran, defatted rice bran and so forth.Low-fat rice bran and defatted rice bran are derived from full-fat ricebran by solvent extraction or the like. Full-fat rice bran has a fatcontent of about 14-18% by weight and low fat and defatted rice branhave about 3-14% and less than 3% fat, respectively, on a weight basis.

As described in the schematic flow sheet shown in FIG. 1, a quantity ofrice bran 10 is placed in a mixer 12. An inactivating enzyme 14 isselected to inactivate the naturally occurring lipase in the rice bran.Suitable materials for this purpose are known to include nonspecificproteases of plant and fungal origin. For example, papain, an enzymenaturally occurring in papaya fruit, and bromelin, an enzyme naturallyoccurring in pineapples, function as suitable antilipase enzymes 14 whenused as described below. Enzeco Fungal Protease brand concentrate, anenzyme fermented from various fungi, also functions as an antilipaseenzyme. Enzeco Fungal Protease brand concentrate is a commerciallyavailable product from Enzyme Development Corporation located in NewYork City, N.Y. All the aforementioned antilipase enzymes appear to workwith substantially the same degree of efficiency. Proteases of bacterialand animal origin (such as pancreatic) may also be useful and mixturesof antilipase enzymes are also contemplated.

In general, freshly milled rice bran 10 has a water content of 20% byweight or less, in general about 10%. As shown in FIG. 1, prior to orconcurrent with enzymatic treatment according to the present invention,the water content of the rice bran is increased to permit the activityof the antilipase enzymes mentioned above, all of which function in anaqueous or hydrated environment. Additional water above the thresholdamount needed to activate the antilipase enzyme in general increases thespeed of inactivation. For example, when water is added to the freshrice bran in a ratio of 1:10 based on weight, the stabilization processtakes approximately 24 hours to complete, whereas when the water to ricebran ratio is 5:1 based on weight, the process will be completed inapproximately five minutes. Rice bran 10 does not become unpalatableeven when the stabilization process takes as long as 24 hours tocomplete. While additional water increases the speed with which the ricebran is stabilized, excessive amounts of water should be avoided as itmust be removed later and increases the processing costs.

With continuing reference to FIG. 1, selected antilipase enzyme 14 isadded to a quantity of water 16 sufficient to wet rice bran 10 andactivate the enzyme. Water 16 is preferably preheated at 18 with steamor the like. Antilipase enzyme 14 is added in an amount effective tosubstantially inactivate the lipase in a selected time that isdependent, as described above, on the amount of water used to wet therice bran. For this purpose, antilipase enzyme 14 is preferably employedat levels of from about 0.01% to about 0.1% by weight. After theantilipase enzyme is added, the mixture is maintained, preferably withcontinued mixing, at a temperature of about 20 degrees C. to about 50degrees C. for a waiting period 20 sufficient for the antilipase enzymeto inactivate substantially all of the naturally occurring lipase in therice bran. Within the above-mentioned ranges, waiting time 20 is shorterat higher temperatures and with higher levels of antilipase enzyme 14.At the end of period 20, rice bran 10 has been processed into a wetstabilized rice bran 22.

As shown in FIG. 1, wet stabilized rice bran can be dried 24 by airdrying, oven drying, vacuum drying, freeze drying or the like to producea dried product 26. The dried product has a moisture content preferablyin the range from about 6% to about 10% by weight and can be stored forlong periods of time without deterioration. Dried stabilized rice branproduct 26 can be rewetted for further processing as shown in FIGS. 2and 3 or used as an ingredient in various food products.

Wet stabilized rice bran 22 (or rewetted dried rice bran 26) can befurther processed as shown in FIG. 2 when it is prepared from rice bran10 which is full-fatted or only partially defatted. Wet stabilized ricebran 22 can be further processed as shown in FIG. 3 when it is preparedfrom rice bran 10 whether it is defatted or not, the nature of theproducts, however, depend on the fat content.

As a first step of further processing in both FIGS. 2 and 3, theinsoluble dietary fiber present in wet stabilized rice bran 22 must beseparated from the water soluble dietary fiber. Soluble dietary fiber isconsidered beneficial but insoluble dietary fiber tends to acceleratethe passage of the rice bran through the human digestive tract so thatonly a small nutritive contribution is realized.

The pH of wet stabilized rice bran 22 affects the way in which theprotein is partitioned when the insoluble dietary fiber is separatedfrom the soluble dietary fiber. More particularly, proteins are moresoluble when the pH is on the basic side. For that reason, it ispreferred that the pH of wet stabilized rice bran 24 be adjusted with apH adjuster 28 so that the pH is from about 7.5 to about 12. In thisrange, most of the proteins stay in water solution and are notdenatured. Suitable food grade bases for pH adjuster 28 include calciumhydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide andso forth. Calcium hydroxide is preferred for nutritional reasons sinceit is a source of additional calcium. If more protein is desired in theinsoluble dietary fiber, the pH of wet stabilized rice bran 22 isadjusted to neutral or acidic. In which case, pH adjuster 28 is a foodgrade acid, suitable ones of which are illustrated below. The exacteffect of the pH of the wet stabilized rice bran and amount of proteinin the insoluble dietary fiber can be determined empirically.

The pH-adjusted, wet stabilized rice bran 22 is wet milled 30 such as ina mixer/grinder into a slurry consisting of a finely ground solid phase32 containing the insoluble dietary fiber and a liquid phase 34. Theprotein and other nutritional components of the rice bran such asstarch, minerals, vitamins and so forth pass mainly with the solubledietary fiber into liquid phase 34. The solid phase is separated 36 fromthe liquid phase by means of a decanter centrifuge or the like. Solidphase 32 can then be dried 38 such as in a spray dryer into a driedfiber product 40.

After the insoluble dietary fiber (fiber product 40) has been separatedfrom liquid phase 34, the liquid phase can be processed into a number ofother products. The nature of the other products depend on whetherliquid phase 34 was derived from a full-fat, partially defatted or fullydefatted rice bran 10. The products also depend on whether the starch inliquid phase 34 is converted into simpler carbohydrates and on theamount of conversion. Subsequent filtration steps also affect the natureof the products as more particularly discussed below.

When liquid phase 34 is derived from a full-fat or only partiallydefatted rice bran 10, the liquid phase can be further processed into amilk-replacer as shown in FIG. 2. When liquid phase 34 is made from afull-fat rice bran 10, a whole-milk milk-replacer is produced, whereas apartially defatted rice bran 10 provides a low-fat milk-replacer. Forthis purpose, it is necessary that the starch in liquid phase 34 beconverted 42 into dextrins and dextroses. This can be accomplished bytreating liquid phase 34 with acid, heat or enzymes or some combinationthereof.

In the production of a milk-replacer as shown in FIG. 2, it is preferredthat the pH of liquid phase 34 be adjusted to about 5.5 to 7.0 with afood grade acid 44. In this range, the proteins are still soluble andnot coagulated and the end products are more palatable for humanconsumption. The minerals and phytin are made more soluble. Mineralacids such as hydrochloric acid and sulfuric acid or organic acids suchas citric acid, fumaric acid, maleic acid or acetic acid and so forthmay be used to achieve the desired pH.

Following pH adjustment, an amylase 46 is added to liquid phase 34 toenzymatically digest the starch into dextrins. Conversion is furtherpromoted by heating the mixture to a temperature in the range of about50 degrees C. to about 60 degrees C. An amyloglucosidase may also beadded to aid in the conversion of the dextrins into glucoses. Acceptableresults have been obtained when the enzymatic digestion is carried outwith from about 0.1 l to about 1.0 l of amylase per ton of stabilizedrice bran 26. When amyloglucosidase is used, it is preferably present ata level of about 0.1 l to about 1.0 l per ton. Amylase is commerciallyavailable as TERMAMYL 1 from Novo Nordisk of Copenhagen, Denmark andamyloglucosidase is commercially available as AMG from Novo Nordisk.

Conversion is allowed to continue until about 80% to about 100% byweight of the starch has been digested into dextrins and glucoses thatwill pass through a 100,000 molecular weight filter. The time necessaryfor this to occur varies from about 15 minutes to about 4 hoursdepending upon the pH of liquid phase 34, the temperature and the amountof amylase (and amyloglucosidase, if present). Preferably, conversionoccurs in about 15 minutes to about 1 hour.

After the desired extent of conversion is completed, liquid phase 34 maybe condensed 48 by removal of some of the water. This may beaccomplished by passing liquid phase 34 through a vacuum evaporatorwhere from about 20% to about 60% by weight of the water is removed. Thefat may then be homogenized 50, if desired, by passing liquid phase 34through a homogenizer.

With continuing reference to FIG. 2, after conversion 42 (andcondensation 48 and homogenization 50, if any), liquid phase 34 isfiltered through a filter having a particle size or molecular weightcut-off such that a retentate 56 contains proteins, fats andcarbohydrate of a selected molecular weight and higher and a permeate 58contains phytin, minerals and vitamins, along with proteins, fats andsugars which pass through the filter. Retentate 56 may be dried 60 in aspray drier or the like into a dried product 62.

Filters suitable for filtering liquid phase 34 are typically membranefilters, sometimes referred to as hollow fibers, spiral wound andceramic filters. A detailed discussion of microfiltration andultrafiltration means can be found in "Ultrafiltration Handbook" by M.Cheryan, Technomic Publishing Co., 1986.

As shown in FIG. 2, liquid phase 34 is passed through a microfilter witha molecular weight cut-off of about 250,000 to about 100,000, morepreferably a molecular weight cut-off of about 100,000.

If products other than a milk-replacer are wanted, liquid phase 34 canbe processed as shown in FIG. 3. The process shown in FIG. 3 can be usedon wet stabilized rice bran 22 derived from defatted as well as full-fatand partially defatted rice bran. The process is identical to that shownin FIG. 2 down to the point that the starches in liquid phase 34 areconverted with acid 44, heat 48 and amylase 46. In this instance,conversion is stopped, preferably after a period of about 10 minutes to30 minutes, or when less than about 80% by weight of the starch has beendigested into simpler carbohydrates that will pass through a 100,000molecular weight filter.

Liquid phase 34 is passed through a microfilter 64 (preferably a 100,000molecular weight microfilter) such that a retentate 66 containscarbohydrates having a molecular weight of 100,000 or higher. Retentate66 can be dried 70 such as in a spray drier to yield a slow-releasecarbohydrate product 72.

Permeate 74 from the microfiltration step can be further passed throughan ultrafilter 76 with a molecular weight cut-off of about 20,000 toabout 10,000, preferably about 15,000 to about 10,000, and morepreferably about 10,000. A retentate 78 on ultrafilter 76 containsproteins and simple sugars having a molecular weight of 10,000 andhigher and a permeate 80 contains phytin, minerals and vitamins, alongwith any proteins and sugars which pass through ultrafilter 76.Retentate 78 can be dried 82 in a spray drier or the like into a driedproduct 84.

Rice products, unlike soy products, are generally non-allergenic. Henceit is anticipated that wet stabilized rice bran 22 and dried products26, 40, 62, 72 and 84 and liquid products 58 and 80 have a similarcharacteristic. For example, dried product 62 can be used as ahypoallergenic milk-replacer either in its dried form or reconstitutedto a liquid consistency. When reconstituted, the solids content can beadjusted by the addition of water to yield a beverage very similar inappearance and taste to milk. Dried product 62 can also be used in awide variety of food formulations as a replacement for milk and sugarsolids. Dried product 84 cannot be used as a milk-replacer but it isuseful for other purposes in food products. Dried product 40 can be usedas fiber in health foods and dried product 72 is a good source ofslow-release carbohydrates. Liquid products 58 and 80 are rich inminerals and phytin and may be used, for example, as an isotonic sportsdrink.

Depending on the product to be produced, in some instances it is notnecessary to stabilize the rice bran before the rice bran is wet milledas shown in FIGS. 2 and 3. In this instance, wet rice bran issubstituted for wet stabilized rice bran 22. Products, like permeate 58and permeate 80, contain very little fat or oil so whether or not therice bran is stabilized is of little importance. Products like retentate66, on the other hand, contain fat or oil. If retentate 66 is intendedfor use, for example in the cosmetic and pharmaceutical industry, thepresence of active lipase may be advantageous. In this instance, thelipases may be used to partially hydrolyze the triglycerides into mono-and diglycerides and are then deactivated by the addition of anantilipase enzyme or the application of heat. Mono- and diglycerides areuseful as emulsifiers.

The following examples illustrate the invention.

EXAMPLE 1 Enzymatic Stabilization of Fresh Rice Bran

A full-fat dried stabilized rice bran 26 was prepared as shown inFIG. 1. To thirty pounds of water 16, five ounces of Enzeco FungalProtease brand concentrate 14 was added and thoroughly mixed. Theaqueous solution was added to 300 pounds of fresh full-fat rice bran 10and mixed in a planetary mixer for 20 minutes (mixing step 12). Themixture was allowed to work for twenty minutes (waiting time 20) at 85degrees F. (heating step 18). The wet stabilized rice bran 22 was thendried to 6% by weight in a forced air oven (drying step 24).

The resulting dried stabilized rice bran 26 had a fatty acid content of1.82% of total oil content after three weeks of storage. The free fattyacid content of unhydrolyzed rice bran is 0.28% by weight. The normalfree fatty acid content in unstabilized rice bran at the same moistureand temperature varies from 35% to 55% of total oil content. Thereduction in free fatty acid present in the product after three weeks ofstorage demonstrates that the lipase enzyme had been deactivated andthat the resulting dried stabilized rice bran 26 should have a longshelf life without deterioration.

EXAMPLE 2 Aqueous Extraction of Full-Fat Rice Bran and Production ofWhole Milk Replacer

The dried stabilized rice bran 26 prepared in Example 1 by the processshown in FIG. 1 was further processed as shown in FIG. 2. 1,250 poundsof water was heated to 82 degrees F. and 250 pounds of full-fat driedstabilized rice bran 26 were added to the water. The pH of the resultantwet stabilized rice bran 22 was 6.7. The pH was adjusted to 9.15 by theaddition of 1,000 ml of 50% sodium hydroxide (pH adjuster 28).

The product was passed through an in-line mixer/grinder (wet mill step30) and then through a decanter centrifuge (separation step 36). Theliquid phase 34 was put through the decanter centrifuge twice and thenthe pH was adjusted from 9.1 to 6.1 with the addition of hydrochloricacid (addition of acid step 44). The solid phase 32 was spray dried(drying step 38) after it was washed with water.

BioCon brand amylase enzyme (addition of amylase step 46) was then addedto convert (conversion step 42) the starch to simpler carbohydrates suchas dextrins and glucoses. BioCon is a trademark of BioCon SystemsCompany in Louisville, Ken.

The product of the conversion went to a Contherm vacuum evaporator andwas flashed to 85 degrees F. (condensation step 48). Solids after thevacuum evaporator were 7.5% by weight as measured by a Cenco moistureanalyzer. Remaining liquid phase 34 was homogenized (homogenization step50). The purpose of the homogenization step was to combine the fats andthe proteins in the liquid. Homogenization typically occurs from 1,500to 15,000 PSI. The first stage of homogenization occurred at 2,000 PSIand the second stage occurred at 500 PSI. The liquid then went through a100,000 molecular weight filter (microfilter step 54). The system used aPolysulfone membrane. The retentate 56 was then spray dried to yield atotal of 1.8 pounds of material from the chamber and 0.47 pounds fromthe cyclones.

The process described above produced the following three products:

1. Fiber product 40.

The analysis of the fiber product was:

    ______________________________________                                        Protein          19.58%                                                       Fat             19.69                                                         Fiber           13.20                                                         Ash             11.11                                                         Carbohydrates   36.42                                                         ______________________________________                                    

2. Whole-milk milk-replacer (dried product 62)

The proximate analysis of the milk replacer was:

    ______________________________________                                        Protein         26.6%                                                         Fat             26.6                                                          Carbohydrates   36.2                                                          Moisture        4.0                                                           Ash             3.0                                                           Fiber           3.6                                                           ______________________________________                                    

3. Isotonic sports drink (permeate 58)

Permeate 58 is rich in phytic acid. Phytic acid comprises as much as 7%by weight of rice bran and at one time was considered an undesirablecomponent. Now, however, phytic acid and its salts are considered to beone of the most profitable constituents. Phytic acid is an inositolphosphate and is used as a chelating agent and surfactant in the surfacecoating and metal industry. When phytic acid is hydrolyzed under certainconditions, it can be converted to inositol, a compound shown to beessential to growth and development. Inositol is used in vitamin mixes,food/feed additives, medicines and cosmetics. Permeate 58 is also richin vitamins, particularly thiamin, riboflavin and niacin.

EXAMPLE 3 Aqueous Extraction of Low-Fat Rice Bran and Production ofLow-Fat Milk Replacer

Following the process shown in FIG. 2, three hundred pounds (136 kg) oflow-fat (9% fat) dried stabilized rice bran 26 was mixed with 1,240pounds (567 kg) of water. The pH initially was 6.3 and was increased to9.35 by the addition of 140 ml of 50% sodium hydroxide (pH adjustmentstep 28 in FIG. 2). The mixture was wet milled (wet milling step 30) andthen passed twice through a decanter centrifuge (separation step 36).

The pH of the liquid phase 34 was adjusted to 6.7 with hydrochloric acid(addition of acid step 44) and heated to 190-200 degrees F. (heatingstep 48) and held for 45 minutes while 100 ml of amylase (addition ofamylase step 46) and some "Edlong", a natural masking flavor, wereadded.

The liquid phase 34 was then evaporated in a Contherm flashed to 85degrees C. (condensation step 48). The product was then homogenized at2,500 PSI, 2,000 PSI first stage and 500 PSI second stage(homogenization step 50). Liquid phase 34 was then microfiltered with a100,000 molecular weight filter. The solids were 16% (refractometer) andweighed 115 pounds. Retentate 56 was spray dried (drying step 60).

The above process produced the following three products:

1. Fiber product 40

    ______________________________________                                               Protein   19.58                                                               Fat       19.69                                                               Fiber     13.20                                                               Ash       11.11                                                               Carbohydrates                                                                           36.42                                                        ______________________________________                                    

The fiber product 40 of Example 3 is like the fiber product 40 ofExample 2.

2. Low-fat milk replacer (dried product 62)

The low-fat milk replacer was a complex of proteins, carbohydrates andfats derived from partially defatted bran.

The proximate analysis was:

    ______________________________________                                        Protein         30.3%                                                         Fat             14.8                                                          Carbohydrates   45.0                                                          Ash             3.0                                                           Moisture        4.0                                                           Fiber           2.9                                                           ______________________________________                                    

3. Permeate 58

The permeate from the 100,000 molecular weight microfilter provides anisotonic sports drink containing phytic acid, vitamins and minerals.Permeate 58 of Example 3 is like permeate 58 of Example 2.

EXAMPLE 4 Extraction of Phytin and Other Products

Using the process shown in FIG. 3, 50 pounds of stabilized rice bran 22(from Example 1) were added to 40 gallons of water. This combination wasmixed for 15 minutes (wet mill step 30) and then pumped to a rotating 80mesh screen (separation step 36). A fiber-rich solid phase 32 and aliquid phase 34 were collected.

Twenty-four liters of liquid phase 34 were placed in a tank and pumpedthrough an AMICON 0.1 micron hollow fiber microfiltration system 64.Pressures were 20 PSI inlet and 10 PSI outlet and the flow averaged 20gallons per minute. Two liters (1) of retentate 66 and 22 l of permeate74 were collected.

Permeate 74 was then filtered a second time through a 30,000 molecularweight cut-off ultrafilter 76. The protein content of retentate 78 was1.0% by weight and the protein content of permeate 80 was 0.8% byweight.

EXAMPLE 5

This example was carried out exactly like Example 4 except that the30,000 molecular weight cut-off ultrafilter 76 was replaced with a10,000 molecular weight cut-off ultrafilter. The protein content ofretentate 78 was 1.5% by weight and the protein content in permeate 80was too low to measure. Permeate 80 of Example 5 is like permeate 58 inExamples 2 and 3.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained. Asvarious changes could be made in the above methods and products withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. A stabilized rice bran made by a method forenzymatically stabilizing rice bran containing protein and having anaturally occurring lipase enzyme that causes rancidity comprising:(a)selecting an antilipase enzyme which inactivates the naturally occurringlipase enzyme in the rice bran; (b) mixing the rice bran with water andthe antilipase enzyme, said antilipase enzyme being in an amounteffective to substantially inactivate the lipase enzyme in a period oftime that is dependent on the amount of water; and, (c) waiting theperiod of time for the inactivation to occur whereby a wet stabilizedrice bran is produced without denaturing the protein.
 2. The stabilizedrice bran of claim 1 wherein the water is present in a water to ricebran ratio of about 1:10 to about 5:1 by weight.
 3. The stabilized ricebran of claim 1 wherein the mixture of rice bran, water and antilipaseenzyme is held at a temperature from about 20 degrees to about 50degrees C. during the waiting period for inactivation to occur.
 4. Thestabilized rice bran of claim 1 wherein the antilipase enzyme is anonspecific protease of plant, fungal, bacterial or animal origin. 5.The stabilized rice bran of claim 1 wherein the antilipase enzyme isselected from the group consisting of papain, bromelin and fungalprotease.
 6. The stabilized rice bran of claim 1 further comprisingdrying the wet stabilized rice bran to produce a dried stabilized ricebran.
 7. A stabilized rice bran made by a method for enzymaticallystabilizing rice bran containing protein and having a naturallyoccurring lipase enzyme that causes rancidity comprising:(a) selectingan antilipase enzyme which inactivates the naturally occurring lipaseenzyme in the rice bran, said antilipase enzyme being a nonspecificplant protease or a nonspecific fungal protease; (b) mixing the ricebran with water in a ratio of about 1:10 to about 5:1 by weight and withthe antilipase enzyme in an amount effective to substantially inactivatethe lipase enzyme; (c) holding the mixture of rice bran, water andantilipase enzyme at a temperature from about 20 degrees C. to about 50degrees C. while waiting the period of time for the inactivation tooccur whereby a wet stabilized rice bran is produced without denaturingthe protein.
 8. The stabilized rice bran of claim 7 further comprisingdrying the wet stabilized rice bran to produce a dried stabilized ricebran.